When Google’s Safe Browsing tool is working at its best, it’s invisible—a silent barrier between you and all the malware, phishing attempts, and other goblins lurking on the web. But every once in a while, you’ll see a glaring red warning when you try to visit a website that tells you to get the hell out of there.

That warning is Safe Browsing letting you know that whatever site you’re trying to visit is trying to lure you into sharing personal information or downloading malware and it’s time to bail. Google announced today that Safe Browsing is now at work on three billion devices—up a whopping one billion from May of last year.

That growth is largely due to Safe Browsing’s expansion on mobile. The tool was initially designed for desktop back in 2007, but Google’s been working to streamline it, making it faster and less battery-consuming for mobile users. Safe Browsing also got integrated into Safari last year and Google started offering it for integration into Android apps, helping it net another billion users.

“Over the last few years, we’ve rethought how Safe Browsing delivers data. We built new technologies to make its data as compact as possible: We only send the information that’s most protective to a given device, and we make sure this data is compressed as tightly as possible,” Stephan Somogyi and Allison Miller of Google’s Safe Browsing team wrote in a blog post.

Google isn’t the only company using the tool; although you’re probably used to seeing it in Chrome, it’s also present in Safari and Firefox and quietly working behind the scenes in major apps like Snapchat.

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Snapchat uses Safe Browsing to vet links that its users share with each other. When you click on a link, Snapchat checks if it’s associated with spam or phishing. “If you open a link of this nature, you’ll see an alert that lets you back out, or learn more about Google’s Safe Browsing service. The URL itself will not be shared with Google,” Snapchat explains on its support site.

So if you’re greeted with a giant red warning—whether its in Chrome, Safari, or Snapchat—just know you’re one of billions of people who were lucky enough not to get phished today.